In a known art, when the temperature of a catalyst is lower than a purification temperature window of the catalyst and the internal combustion engine is operating in an accelerating state, if the exhaust gas temperature is higher than the catalyst temperature, the degree of opening of a throttle valve is decreased and the degree of opening of an EGR valve is decreased, to thereby raise the temperature of the catalyst quickly (see, for example, patent literature 1).
In another known art, in a system adapted to decrease the intake air quantity and retard the fuel injection time when the temperature of a selective catalytic reduction catalyst is lower than a purification temperature window, the lower the temperature of the selective catalytic reduction catalyst is, the more the intake air quantity is decreased (see, for example, patent literature 2).
In another known art, in an exhaust gas purification apparatus for an internal combustion engine adapted to perform fuel addition control for supplying unburned fuel component to a catalyst provided in the exhaust system of the internal combustion engine, when the intake air quantity is larger than a predetermined quantity set as a function of the temperature of the catalyst, the quantity of the unburned fuel component to be supplied is decreased (see, for example, patent document 3).
In another known art, in a system adapted to restrict the fuel injection quantity to an upper limit value when a base fuel injection quantity determined based on the load of the internal combustion engine is larger than the upper limit value, the upper limit value is set smaller when the amount of PM trapped in a particulate filter is large than when it is small (see, for example, patent literature 4).
In another known art, in an exhaust gas purification apparatus having an oxidation catalyst provided in the exhaust system of an internal combustion engine, the fuel injection quantity is restricted so that the temperature of the oxidation catalyst does not exceed the upper bound of an allowable temperature range (see, for example, patent literature 5).